For this chapter, we have collated from the authors in this book approaches and techniques for the quantification and qualification of biofouling and have presented most of it in referenced tabular form to permit easy access to the information (Table 22.1). There are also two more thorough sections neither of which has been published before: one on the sampling of hulls of large vessels and another which details a broadly applicable advanced stereo logical techniquefor the quantification of fouling. The collection is unlikely to be fully comprehensive, but we have aimed to give the reader techniques for quantification of different levels of the biofouling community, from biofilm to macroorganisms, and from single species to the whole community. The techniques are for use in the office, laboratory or the field and range from cheap to costly. All of these techniques have proven their usefulness and with this chapter we would liketo improve the exchange of approaches to biofouling quantification between the different disciplines. For this reason, the techniques come from across the basic and applied sciences in industry, biology and medicine.